Samples, such as material containing DNA, are currently processed both manually and automatically in vessels, such as centrifuge tubes. In many lab processes, a sample of some material which contains components to be isolated, mixed, or the like is typically placed in a sample vessel.
Typical lab procedures for working with samples include mixing and agitating the sample, adding material to the sample, removing material from the sample by pouring, and the like. These processes have traditionally been performed by hand. However, some methods of isolating components involve automated methods.
Some laboratory procedures require the user or the machine to pour-off a portion of the mixture and retain the other portion, for example a supernatant is poured off and one or more pellets are retained for further processing. This pour-off process can be very delicate, and if not done carefully, can result in lost pellets. In the case of unique or limited samples, or samples which require long development cycles, such errors can be devastating when the samples cannot be duplicated, or are irreplaceable. This is especially true for automated methods, as such pour-off techniques can be performed more delicately by humans than by machines.
Furthermore, during precise laboratory procedures, such as DNA or RNA isolation, pellet loss can also cause contamination and cross-contamination of samples and the laboratory, such that the entire process needs to be restarted.
One approach in facilitating pellet retention is shown in U.S. Pat. No. 5,234,667, which includes a micropitted roughened portion within a micro-centrifuge tube. However, this approach as described by Radtke et al. is intended for μL-sized samples and is not scalable for use with 1 mL or larger samples, and still results in pellet loss. See Example 1 described further below.
Accordingly, what is needed is a process and vessel which prevents inadvertent loss of samples during processing, such as during the pour off process.